Magnetic separator



July 3, .1934. E. o. E. TYDEN 1,965,441

MAGNETI C SEPARATOR Filed July 15, 1931 2 Sheets-Sheet 1 V fi/forney.

July 3, 1934. Q YDE 1,965,441

MAGNETIC SEPARATOR Filed July 13, 1931 2 Sheets-Sheet 2 In yen/a7":

Patented July's, 193

REAGNETIC SEPARATOR 'Einar Oloi Eugen Tydn, Stockholm, Sweden, as signer of one-third to Gunnar Sigge Andreas Appelavist and one-third to Carl Theodor Setterberg, both of Stockholm, Sweden Application July 13,1931, Serial .No. 550,321 .111 Sweden December 23, 1930 1 Claim. (Cl. 209--219) The present invention relates to an improvement in magnetic separators of the type which are. provided with a cylinder, or several cylinders, of magnetic material, usually soft iron, which is rotatably journalled between two magnetic pole pieces, and in which the material to be separated is caused to pass between said cylinder and one of thepole pieces. lhe invention has for its purpose to provide an improved construction of such separators by means of which also very weakly magnetic material may be eiiectively separated from non-magnetic material.

For this purpose the present improvement consists principally in that the rotatable cylinder is provided on its surface with ridges, which are parallel or substantially parallel to the axis of the cylinder, and that the pole pieces are wedgeshaped or tapered in such manner that they form edges which are directed towards and parallel or substantially parallel with the ridges on the cylinder. By'this arrangement a'very strong concentration of the magnetic field isobtained between the edges of the pole pieces and the ridges on the cylinder, so that also very weakly magnetic material is attracted by the ridges and is carried along, during the rotation of the cylinder, so far that it is separated from the non-attracted, wholly non-magnetic material. Suitably, in order still further to increase the field concentration, the ridges on the cylinder may also be wedgeshaped, so that they form edges which are parallel or substantially parallel with the edges of the pole pieces, and the grooves between the ridges may be wholly or partially filled with a nonemagnetic material, such as rubber, lead, or the like,

in order to preventthe attracted magnetic material from sticking in the grooves.

,"Heretofore magnetic separators have been constructed with only one magnetic core for each pole piece, which renders it difiicult to obtain a uniform distribution of the lines of forcein the entire portion of the pole piece directed towards the cylinder, and for this reason such separators have necessarily been restricted to a comparatively small length of the cylinder.

According to the present invention a plurality of magnetic cores are attached to each pole piece, suchcores being preferably placed in a row parallel to the edge of the pole piece. With this arrangement the cylinder and the pole pieces may of example various constructional forms of the invention. Fig. 1 shows inside view and partly in section a magnetic separator according to the invention, and Fig. 2'shows the separator in top plan view, the feed chute for supplying the materialto be separated, being removed. Fig. 3 shows diagrammatically a'second constructional form of a separator according to the invention in end view, and Fig. 4 shows the same in plan view. Fig. 5 shows an end View of a third constructional form.

The magnetic separator illustrated in Figs. 1 and 2 is provided with four cylinders 1, 2, 3, and 4, which are rotatably journalled one above the other, and which are adapted to operate in series, so that the material to. be separated is first fed to the uppermost cylinder 1, from which such material as is not attracted to said cylinder, is conducted to the next cylinder 2, and so forth.

Each cylinder is rotatably journalled between two pole pieces5 and. '6, '7 and 8, 9 and 10, and 11 and 12, respectively, of two powerful electromagnets 13 andl l, each of which has four pole pieces, namely two at each end. Each cylinder may suitably consist of a number of thin laminations of soft sheet iron magnetically insulated, which are placedon a shaft 15 of non-magnetic material, for instance brass, and are pressed against each other by means of thick end plates 16 secured to the shaft.

All of the cylinders 1 to 4, inclusive, are provided on their surface with wedge-shaped ridges 1'7, and, as shown in Fig. l, the pole pieces 5 to 12, inclusive, are also wedge-.shaped'in such manner that they form edges which are directed towards and are parallel with the ridges on the cylinders. The two uppermost cylinders 1 and 2, in Fig. l, are intended to rotate in the clockwise direction, while the two lowermost cylinders 3 and 4 rotate in the opposite direction, as indi cated by the arrows. The rotational speed of the cylinders is adjusted to suit the material to be treated, and should as a rule be 20c to 300 revolutions per minute. Provided below each cylinder 1, 2, 3, 4, is a chute 18, 19, 20, and 21, respectively, for collecting the particles attracted tothe 'cylindelyand also a chute 22, 23, 2s, and 25, respectively,'for collecting the non-attracted material and conducting such material to the next cylinder.

The material to be separated, is supplied through a feed chute 26 from which it passes downwards through the narrow space between the cylinder 1 and the pole piece 6 on the descending side of said cylinder, said pole piece being suitably placed slightly lower than the opposite pole piece 5, as illustrated in the drawings. Due to the wedge-shape of the pole piece 6 and of the ridges 1'7 a very strongly concentrated magnetic field is produced in said space, so that also weakly magnetic particles in the material are attracted to the ridges 17 on the cylinder 1, and are caused to follow said cylinder through approximately a quarter of a revolution, after which said particles drop and are collected in the chute 18. The non-attracted material, on the other hand, drops into the chute 22 through which it is conducted to the next cylinder 2. The described course is repeated at said cylinder 2, as well as at the cylinders 3 and 4, so that the material which finally passes between the pole piece 11 and the cylinder 4 without being attracted to the ridges on the latter, is practically completely free from magnetic constituents.

The separator illustrated in Figs 3 and 4 comprises a cylinder 31, which is rotatably journalled between two pole pieces 32 and 33, which are supported by electromagnets 34 and 35, which are placed on a common yoke or bottom plate 36. For each pole piece there are provided, according to the embodiment shown, four electromagnets 34 and 35, respectively, as shown in Fig. 4.

The cylinder 31 is preferably provided on its surface with ridges 37 which may be parallel to the axis, or substantially parallel to the same in such manner that they run slightly obliquely to the axis, as will be seen in Fig. 4. The cylinder may suitably consist of magnetically insulated disks or laminations of soft sheet iron. The pole pieces 32 and 33 are suitably wedgeshaped in such manner that they form edges which are directed towards and parallel, or substantially parallel, to the ridges 3'? on the cylinder. Provided below the cylinder is a chute 38 for collecting the particles attracted by the cylinder, and also a chute 39 for receiving the non-attracted material. The material to be separated, which may be wet or dry, is supplied by means of a feed chute 40 from which it passes down through the narrow space between the cylinder 31 and the pole piece 33 on the descending side of said cylinder, which pole piece may suitably be located somewhat lower than the opposite pole piece 32. Owing to the wedge-shape of the pole piece 33 and of the ridges 37 a very strongly concentrated magnetic field is obtained in said space, so that also weakly magnetic particles in the material are attracted by the ridges 37 on the cylinder 31 and are caused to follow said cylinder through approximately a quarter of a revolution, after which they drop and are collected in the chute 38. The non-attracted material, on the other hand, falls directly into the chute 39 and is removed through the same.

The arrangement of several magnet cores for each pole piece provides the advantage that the distribution of lines of force in the pole piece edges becomes as uniform as possible, so that the magnetic field between the edges and the ridges on the cylinder becomes as equally concentrated as possible along the entire length of the cylinder. In this manner it becomes possible to build the separator with practically any desired length of the cylinder and thus with a very high capacity. The advantage is also attained that the magnet coils can be cooled in a simple manner, so that overheating of the same is avoided. By using several smaller magnet cores and coils instead of one big core, the manufacturing cost is also reduced.

Fig. 5 shows an embodiment according to which the separator consists of several superimposed groups or sections, each group comprising a cylinder and cooperating pole pieces with associated magnet cores. The lower group or section, which comprises a cylinder 31, pole pieces 32 and 33, magnet cores 34 and 35, base plate 36, and discharge chutes 38 and 39, corresponds to that shown in Fig. 3. Supported on the pole pieces 32 and 33 are further magnet cores 44 and 45, which support pole pieces 42 and 43 between the edges of which a second cylinder 41 is rotatably journalled. The material to be separated is supplied through the feed chute 40 to said upper cylinder 41, from which the attracted magnetic particles drop into the chute 48, while the non-attracted material falls into the chute 49 through which it is conducted to the lower cylin der 31, where the course is repeated.

The movement of the material through the separator may be facilitated and accelerated by means of a current of air which is directed through a nozzle 50 down into the space between the cylinder 41 and the pole piece 43 and then continues through the chute 49 toward the space between the cylinder 31 and the pole piece 33, where the flow of air can also be produced or supported by means of suction from the chute 39.

Also with this construction several magnet cores may, of course, be attached to each pole piece in the manner diagrammatically illustrated in Fig. 4.

In all of these embodiments the cylinder or cylinders as well as the pole piece edges may be slightly inclined to the horizontal plane in the axial direction, which arrangement has proved to be of advantage particularly in the treatment of wet material, since in such case the water flows oiT more easily from the grooves between the ridges on the cylinder.

The constructions illustrated in the drawings are only to be regarded as examples, and it will be understood that the same may be modified in several ways as regards their details without departing from the principle of the invention as defined in the following claim.

I claim:

In a magnetic separator, the combination of two magnetic pole pieces, a cylinder of magnetic material rotatably journalled between said magnetic pole pieces, said cylinder being provided on its surface with ridges substantially parallel to the axis of rotation of the cylinder, said pole pieces being wedge-shaped in such manner that they form edges which are directed towards and substantially parallel to the ridges of the cylinder, and a plurality of magnet cores attached to each pole piece and placed in a row parallel to the pole piece edge.

EINAR OLOF EUGEN TYDEN. 

